1. Field of the Invention
The present invention relates to an apparatus for generating a recording signal including image data and control information intended for preventing the illegal copying of the image data, an apparatus for making a copy of the image data according to the control information, and a recording medium on which the image data and the control information are recorded.
2. Description of the Related Art
Generally, the image data or image information of movies or the like is protected by the copyright in many cases. The unauthorized copying of the image data protected by the copyright is basically prohibited. Therefore, a method is required to effectively prevent the illegal copying of the image data.
The illegal copying of the image data based on the NTSC (National Television System Committee) system is generally prevented by the method described below. Specifically, the copy condition information (hereinafter referred to as xe2x80x9cCCIxe2x80x9d) is embedded beforehand in the portion of the signal containing image data which corresponds to the vertical blanking time. This CCI contains information indicating that copying the image data is prohibited or information indicating that copying the image data is permitted only once. Upon detection of the CCI when copying image data, it is possible to recognize whether the image data can be copied or copying it is prohibited.
However, the portion of the signal containing the image data which corresponds to the vertical blanking time performs the function of what is called the synchronizing signal. Therefore, this portion is not important as image data. This portion is often removed in signal processing such as the digitizing process. In the digitizing process for recording image data on a DVD, for example, the signal portion corresponding to the vertical blanking time is replaced with other synchronizing signals suitable for the digitizing processing.
When this digitizing process is executed, therefore, the CCI embedded in the portion corresponding to the vertical blanking time is lost. As a result, the copying of the image data cannot be effectively prevented by CCI.
It is therefore an object of the present invention to provide an image recording signal generating apparatus, an image recording signal recording apparatus, an copying apparatus, and a recording medium which can prevent the loss of the control information including the copy control information such as CCI and thus can prevent the illegal copying.
The above-mentioned object can be achieved by a recording signal generating apparatus according to the present invention. The recording signal generating apparatus is an apparatus for generating a recording signal by converting an image signal and outputting the generated recording signal to an external device. The image signal includes image data corresponding to an image to be displayed on a display screen of a display device. The image data includes a plurality of data pieces each corresponding to different one of a plurality of image elements which compose the image. The recording signal generating apparatus includes: a control information placing device for placing a control information piece onto one of the plurality of data pieces corresponding to one of the plurality of image elements that is to be located at an outer edge portion of the image when the image is displayed on the display screen; and a generating device for generating the recording signal by converting the image signal including the reproduction control information piece. The control information piece includes information to control an operation of the external device. In addition, the external device is, for example, a signal recording device, a signal transmission device, a signal reproducing device, a copying device, signal processing device or the like.
In this apparatus, the control information piece is placed onto one of the plurality of data pieces corresponding to one of the plurality of image elements that is to be located at an outer edge portion of the image when the image is displayed on the display screen. That is, the control information piece is placed onto an outer edge portion of the image. This means that the control information piece is contained in the image data. In other words, it becomes part of the image.
Therefore, as long as contents of the image data is not directly or drastically changed, the control information piece is maintained. Accordingly, the control information piece is maintained, if a process of converting a format of the image data into a different one while keeping contents of the image data, such as the aforementioned digitizing process, is carried out. Accordingly, it can be prevented that the control information piece is removed from the image.
In addition to this advantage, since the control information piece is placed onto the outer edge portion of the image, the control information piece is inconspicuous or invisible when the image is displayed on the display screen. For example, when the image is displayed on the display screen of a typical display device, the outer edge portion of the image is hidden by a screen frame or the like. In this case, the control information piece is invisible. Although the whole of the image is displayed in a visible state in another type of display device, the control information piece is located at the outer edge portion of the image, so that it is inconspicuous. Accordingly, the degradation of the quality of the image can be prevented.
The control information piece may include copy condition information indicating whether or not copying the recording signal is permitted. Therefore, the copy condition information can be always maintained, so that the image can be protected from illegal copying or the like.
Further, a copy protection information placing device may be added to the aforementioned recording signal generating apparatus. The copy protection information placing device is a device for placing a plurality of copy protection information pieces onto a plurality of data pieces each corresponding to different one of the plurality of image elements that is to be located at a part of the image to be displayed within a visible region of the display screen. Each of the plurality of copy protection information pieces is a watermark, for example. Further, information to identify the data piece on which the control information piece is placed may be placed onto the copy protection information pieces. Therefore, an authorized reproduction or copying apparatus can correctly detect the control information piece according to the copy protection information pieces. However, the effect of copy protection can be made strong, because it is very difficult or almost impossible for an unauthorized reproduction or copying apparatus to find the control information piece.
Furthermore, if each of the plurality of data pieces is pixel data corresponding to a pixel of the image, and if the pixel data includes a luminance value representing luminance of the pixel, the control information placing device places the control information piece onto the pixel data by replacing its luminance value with the control information piece. In this case, it is preferable that the control information placing device has: a calculation device for calculating an average of a first luminance value included in the data piece (i.e., pixel data) previous to a target data piece onto which the control information piece is to be placed and a second luminance value included in the data piece next to the target data piece; a generation device for generating the control information piece by changing the calculated average depending on whether or not copying the recording signal is permitted; and a replacing device for replacing the luminance value of the target data piece with the generated control information piece. Thus, the control information piece is generated on the basis of the an average of luminance values included in the neighboring data pieces located at both sides of the target data piece. Therefore, the value of the control information piece is close to these luminance values. That is, although the value of the control information is changed depending on whether copying the recording signal is permitted or not, a difference between the value of the control information piece and the luminance values of the neighboring data pieces is small. Consequently, the control information piece can be placed onto the image in such a way that it is inconspicuous or invisible, so that it can be prevented the degradation of the image.
The above-mentioned object can be also achieved by a signal recording apparatus according to the present invention. This apparatus can generate a recording signal by converting an image signal and record the generated recording signal onto a recording medium readably by an external device for reproducing the recording signal. The image signal includes image data corresponding to an image to be displayed on a display screen of a display device. The image data comprising a plurality of data pieces each corresponding to different one of a plurality of image elements which compose the image. The signal recording apparatus includes: a control information placing device for placing a control information piece onto one of the plurality of data pieces corresponding to one of the plurality of image elements that is to be located at an outer edge portion of the image when the image is displayed on the display screen; a generating device for generating the recording signal by converting the image signal including the reproduction control information piece; and a recording device for recording the generated recording signal onto the recording medium. The control information piece includes information to control an operation of the external device. Therefore, the image data including the control information can be recorded on the recording medium.
The above-mentioned object can be achieved by a recording medium according to the present invention. On this recording medium, reproduction data intended for a reproduction of an image is recorded. This reproduction data includes image data corresponding to the image to be displayed on a display screen of a display device. The image data includes a plurality of data pieces each corresponding to different one of a plurality of image elements which compose the image. Further, the reproduction data includes: a copy condition information piece placed on one of the plurality of data pieces corresponding to one of the plurality of image elements that is to be located at an outer edge portion of the image when the image is displayed on the display screen. The copy condition information piece indicates whether or not copying the image data is permitted.
In the reproducing data, the copy condition information piece is placed on an outer edge portion of the image. Therefore, as long as contents of the image data is not directly or drastically changed, the copy condition information piece is maintained. Accordingly, it can be prevented that the copy condition information piece is removed from the image, so that it can be effectively prevented illegal copying. In addition to this advantage, since the copy condition information piece is placed on the outer edge portion of the image, the copy condition information piece is inconspicuous or invisible when the image is displayed on the display screen. Accordingly, the degradation of the quality of the image can be prevented.
Further, in the recording medium, a plurality of copy protection information pieces may be added to the reproduction data. In this case, the copy protection information pieces are placed on a plurality of data pieces each corresponding to different one of the plurality of image elements that is to be located at a part of the image to be displayed within a visible region of the display screen. Further, these copy protection information pieces includes information to identify the data piece on which the copy condition information piece is placed. Therefore, when the reproduction data is read out and reproduced from the recording medium by an authorized reproduction or copying apparatus, such an apparatus can correctly detect the control information piece. However, the effect of copy protection can be made strong, because it is very difficult or almost impossible for an unauthorized reproduction or copying apparatus to find the control information piece. In addition, it is preferable that each of the copy protection information piece is a watermark.
The above-mentioned object can be achieved by an copying apparatus according to the present invention. This copying apparatus is an apparatus for copying reproduction data intended for reproducing an image with an external device. The reproduction data includes image data and a copy condition information piece, as stated above. The copying apparatus includes: an extraction device for extracting the copy condition information piece from the reproduction data; a determination device for determining on the basis of the extracted copy condition information piece whether or not copying the image data is permitted; and a copying device for copying the reproduction data if the determination device determines that copying the image data is permitted. Thus, by using this copying apparatus, it can be restricted copying the reproduction data. Therefore, it can be prevented illegal copying.
Furthermore, in this copying apparatus, a replacing device may be added to the copying device. The replacing device is a device for replacing the copy condition information piece currently placed on the data piece included in the image data with a new copy condition information piece indicating that copying is prohibited.
For example, if the current copy condition information indicates that copying is permitted, a copy of the reproduction data may be made. When the copy of the reproduction data is actually made, and it is recorded onto a recording medium for example, there is a case where it is needed to place this copy of the reproduction data into the state that it is not allowed to copying any more. In order to implement this, The replacing device replaces the currently copy condition information piece with the new copy condition information piece indicating that copying is prohibited.
The nature, utility, and further feature of this invention will be more clearly apparent from the following detailed description with respect to preferred embodiments of the invention when read in conjunction with the accompanying drawings briefly described below.